Friday, January 15, 2016

More on the beauty question

Here’s my review of Frank Wilczek’s book A Beautiful Question: Finding Nature’s Deep Design, which appeared in Physics World last year.

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There aren’t many books on which you will find admiring blurbs by both Lawrence Krauss and Deepak Chopra, but this is one. You can see why. Wilczek writes in a freewheeling, almost poetic way, while retaining a penetrating and rigorous vision of what he wants to say about physics, science and the world.

His opening question – “Is the world a work of art?” – sets the tone: at the same time lyrical and baffling. Wilczek’s answer, as you might guess from the title, is “Yes, and it’s a beautiful one.” He reaches this conclusion after surveying the central role that symmetry plays in modern physics, from the shapes of atomic orbitals to the structure of quantum chromodynamics. He makes one of the most compelling cases I have seen for why symmetry can be considered a guiding principle worth heeding in efforts to push back the frontiers of physical theory. The latest prospect of doing that – of expanding fundamental physics beyond the Standard Model, which Wilczek prefers to call the Core Theory – comes from the principle of supersymmetry, which promises to unify bosons (“force particles”, with integer spin) and fermions (“substance particles”, with half-integer spin). This idea looms large on the agenda of the Large Hadron Collider now that it has returned to operation after an upgrade. Thanks to Wilczek, I now have a better sense of why the theory not only might be true but ought to be.

All the same, if this were a regular popular science book then it would be considered something of a mess. Like poetry, Wilczek’s prose is often highly concentrated thought, and he doesn’t always bother to unravel it or even to define his terms. Even with the glossary, I’m not sure how much the uninitiated reader will get from statements such as “Color gluons are the avatars of gauge symmetry 3.0.” What seem to be more straightforward concepts, such as light perception by the eye, become reconfigured into shapes that, while fitting into Wilczek’s intellectual framework, take time to decrypt: “When we perceive a color, we see a symbol of change, not anything that changes.”

Wilczek’s suggestion that, when the going gets tough, we read the text like poetry rather than hoping to understand all it says, seems optimistic. But these challenges aren’t, I think, exactly defects of the book, because this is not a regular science book. Like Stephen Hawking's A Brief History of Time, it is instead the unique vision of a brilliant mind (with that added advantage that it doesn’t pretend otherwise). For every baffling passage there are other moments when Wilczek explains something in a way that no one else has, or perhaps could, so that you come away with a fresh perspective on something that you thought you understood already. Never again will I be frustrated by pop-science suggestions that Einstein simply decided to posit the constancy of the speed of light: of course he didn’t, and Wilczek cuts straight to the physics of the matter. Put simply, he sees things differently, and that’s the true and compelling reason to read the book.

For the fact is that this book is not a work of explanation but, like Plato’s Timaeus, an extended argument – indeed, what you might call a gentle polemic. It wants to steer us towards Wilczek’s own answer to his initial question. And so, quietly and soberly, he marshals facts that fit his case and soft-pedals ones that don’t. That’s fine – it is what polemics do – so long as we recognize what’s happening. For example, in his discussion of Pythagorean musical consonance he gives us a simple (albeit speculative) physical mechanism for why we prefer harmonies with simple frequency ratios while all but ignoring the fact that we plainly don’t: unless you’ve heard music played in tunings other than equal temperament, you’ll never have heard the interval of a Pythagorean fifth. And the discussion of Chinese yin and yang glosses over the fact that it not an aesthetic idea but a philosophical one: beauty is never, to my knowledge, mentioned by Chinese philosophers in this context.

Such goal-directed argument is most apparent in Wilczek’s discussion of beauty itself, for which the closest thing he gives to a definition is “symmetry and economy of means”. But neither of these features plays a key role either in most art or in most theories of aesthetics. Immanuel Kant, who made one of the most searching enquiries into the nature of beauty, argued that there is something repugnant in too much order and regularity. Even Francis Bacon asserted that “There is no excellent beauty that hath not some strangeness in the proportion”.

Kant’s careful distinction between real beauty and the intellectual satisfaction of perceiving an idea is precisely what physicists ignore when, like Lewis Carroll’s Humpty Dumpty, they make the word mean just what they want it to mean. Wilczek at least admits that not all types of beauty are included in his picture; but the physicists’ usual conception of beauty is Platonic in the extreme and barely if at all relevant to the arts. For Plato it was precisely art’s lack of symmetry (and thus intelligibility) that denied it access to real beauty: art was just too messy to be beautiful. It seems clear, and important, that many physicists do feel a kind of transcendent joy in the symmetries of nature’s laws. But if they really want to talk about it in terms of beauty, they should acknowledge that there is an intellectual heritage to that notion that they will have to confront.